Student is a compound sign: first, sign learn, then sign the person or agent marker. Sign learn by holding your non-dominant palm up, then taking your open dominant hand and spreading your curved fingers on your other palm. Next, pull your dominant hand up such that your fingers close into a flat O hand as you touch them to your forehead.
Finish off by signing the person or agent marker, holding both flat, open hands in front of your body with palms facing each other, then sliding both parallel hands downward.
Teach your toddler the student sign when they are ready to apply this concept to themselves, having begun rudimentary preschool classes for Math, Spelling, and Reading. You can also teach this sign to them when they see their older siblings in school uniforms or porting their backpacks and lunch boxes as they hie off in the family car or school bus.
This is a useful flash card taught best in conjunction with other school or study-centered signs.